Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 527409f651c52b8e…

MALICIOUS

Office (OLE) / .XLSX

143.9 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: 56a7c7fc1eb4ec2e6789d173d66b8de4 SHA-1: 0c74424475b9efb971d6bb81c3f7d95e65fb0408 SHA-256: 527409f651c52b8ef556ca856e1a15af2b35dc6b46f6e38f3ff636a92d2ee9b2
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. ClamAV detection identifies it as 'Xls.Downloader.Emotet', strongly suggesting Emotet family involvement. The critical heuristics indicate the use of dangerous formula APIs within the XLM macro, confirming its malicious intent to download and execute further stages.

Heuristics 4

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • ClamAV: Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
46284ea41c691066b9fe85a87bc7e9bfc77336182ea3b4ed700574b0c8cd3189
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3141 bytes